This application is the national phase under 35 U.S.C. xc2xa7371 of PCT International Application No. PCT/JP00/02264 which has an International filing date of Apr. 7, 2000, which designated the United States of America and was not published in English.
The present invention relates to an agent for protecting pancreatic cells or an agent for ameliorating hypofunction of pancreatic cells, or an agent for protecting pancreatic tissues or an agent for ameliorating hypofunction of pancreatic tissues, these agent comprising as the active ingredient a neurotrophic factor.
Pancreas is an organ consisting of the endocrine gland tissues called pancreatic islet (Langerhans islet) and the exocrine gland tissues secreting digestive enzymes such as amylase, lipase, protease, etc. In the Langerhans islet, B cells (xcex2 cells) synthesizing and secreting insulin, etc., A cells (xcex1 cell) synthesizing and secreting glucagon, etc., D cells (xcex4 cells) synthesizing and secreting somatostatin, and pancreatic polypeptide cells (hereinafter, referred to as PP cells) synthesizing and secreting pancreatic polypeptide, etc. exist, and they greatly affect the control of blood glucose and metabolism. Disorders of these endocrine glands and exocrine glands may induce abnormalities of controlling blood glucose level (e.g., diabetes mellitus, hypoglycemia, insulin shock, etc.) and decreased digestion (e.g., steatorrhea, etc.), respectively.
Pancreatic function disorders are induced by various causes, and representative underlying diseases thereof are, for example, pancreatitis or diabetes mellitus. Pancreatitis is clinically classified into acute pancreatitis and chronic pancreatitis, and the former is mono-pancreatitis or repetitive pancreatitis being characterized by acute bellyache attack accompanied by increase in pancreatic enzyme level in blood or urine. Serious acute pancreatitis further induces necrosis and hemorrhage of pancreatic substratum, serious renal failure, or respiratory failure, and may results in shock to death. The treatment thereof is usually carried out by inhibiting pancreatic exocrine by fasting and an H2 blocker, and further by preventing complications by administering a protease inhibitor, an antibiotic, or an analgesic.
Chronic pancreatitis is mainly induced by over-uptake of alcohol, and characterized by repetitive or persistent bellyache. Morphologically, it is characterized by immethodical sclerosis accompanied by destruction and permanent dissipation of pancreatic exocrine tissues, and it induces symptoms caused by pancreatic exocrine grand failure such as steatorrhea. In chronic pancreatitis, it is observed that about 50% of the patients produce a complication of diabetes mellitus due to pancreatic endocrine disorder (pancreatic diabetes). The characteristic of the secondary diabetes of this chronic pancreatitis is the lack of both insulin and glucagon, and the treatment thereof is mostly carried out by administration of insulin. About half of the causes of death for chronic pancreatitis are concerned with diabetes mellitus, and hypoglycemia after insulin injection (i.e., insulin shock) caused by the lack of glucagon or diabetic complications such as nephropathy or infections are pointed out as a cause of death.
In addition, sulfonylurea derivatives having an insulin secretion promoting activity have been used in the treatment of diabetes mellitus, but they may occasionally induce pancreatic cell dysfunction or pancreatic tissue dysfunction, due to excessive burden on the pancreas by forcing the pancreas to secrete insulin.
At present, a method for promoting a spontaneous recovery of pancreatic function has been used in the treatment of pancreatic function disorder, by eliminating diseases or factors that are a cause therefor (cf., xe2x80x9cLearning of Pancreatopathyxe2x80x9d, edited by Tadashi TAKEUCHI, published by Nankodo Co. Ltd., Aug. 1, 1993), but there in have not been known or used any method or agent for aggressively recovering the decreased pancreatic function.
On the other hand, neurotrophic factors are a generic name for proteins, which are provided from target cells or neurons and glia cells and Schwann cells in the living body. They show activities of maintaining the survival and differentiation of neurons, and are classified into many types according to the kinds of nerves or receptors to function. Among them, proteins being known as neurotrophins have high structural homology with each other and form a family. The typical examples thereof are neurotrophins such as nerve growth factor (hereinafter, abbreviated as NGF), brain-derived neurotrophic factor (hereinafter, abbreviated as BDNF), neurotrophin 3 (hereinafter, abbreviated as NT-3), neurotrophin 4 (hereinafter, abbreviated as NT-4), neurotrophin 5 (hereinafter, abbreviated as NT-5), or neurotrophin 6 (NT-6); ciliary neurotrophic factor (hereinafter, abbreviated as CNTF); glia cell-derived neurotrophic factor (hereinafter, abbreviated as GDNF), etc. In addition, neurotrophins are known to act as a specific ligand of receptors (trkA, trkB and/or trkC), which are the products of p-75 and trk genes (cf. Takeshi NONOMURA, Hiroshi HATANAKA; Jikken Igaku, vol. 13, p. 376 (1995)).
Neurotrophic factors have been studied with respect to their medical use as a therapeutic agent for treating a patient of neurodegenerative diseases. For example, Society for Neuroscience, vol. 21, p. 1535 (1995), A. P. Mizisin et al. discloses the pharmacological activity of BDNF on diabetic peripheral neuropathy, but this literature merely suggests the possible pharmacological activity of BDNF on neuropathy based on the finding that BDNF improves the reduction of motor nerve conduction in vivo. WO 98/32458 discloses that neurotrophic factors such as BDNF can normalize the blood glucose level of diabetic animal models, and applications thereof onto the treatment of diabetes mellitus are disclosed therein.
As mentioned above, an agent for protecting pancreatic cells or an agent for ameliorating damaged pancreatic cells, an agent for protecting pancreatic cell function or an agent for ameliorating pancreatic cell hypofunction, or an agent for protecting pancreatic tissues or an agent for ameliorating damaged pancreatic tissues, or an agent for protecting pancreatic tissue function or an agent for ameliorating pancreatic tissue hypofunction has been desired in the medical field.
The present inventors have an interest in that the insulin secretion of BDNF-treated type 2 diabetic animal models is kept at high level, and have studied pancreatic function ameliorating activities by using type 2 diabetic animal models. As a result, they have found that BDNF can (1) increase the decreased insulin content in pancreas of type 2 diabetes animal models, (2) reduce the increased glucagon content in pancreas, (3) normalize the localization of A cells and D cells in the pancreatic Langerhans islet, (4) promote the re-granulation of insulin secretory granules of B cells in the pancreatic Langerhans islet, and normalize the organellae. Based on the finding of these pancreatic function ameliorating activity and pancreatic cell protecting activity of BDNF, the present inventors have further studied and have accomplished the present invention.
More particular, the present invention relates to the following:
1. An agent for protecting pancreatic cells or an agent for ameliorating damaged pancreatic cells, which comprises as the active ingredient a neurotrophic factor;
2. An agent for protecting pancreatic cell function or an agent for ameliorating pancreatic cell hypofunction, which comprises as the active ingredient a neurotrophic factor;
3. An agent for protecting pancreatic tissues or an agent for ameliorating damaged pancreatic tissues, which comprises as the active ingredient a neurotrophic factor;
4. An agent for protecting pancreatic tissue function or an agent for ameliorating pancreatic tissue hypofunction, which comprises as the active ingredient a neurotrophic factor;
5. The agent for protection or amelioration of the function according to the above 1 or 2, wherein the pancreatic cell is B cells (xcex2 cells), A cells (xcex1 cells), and/or D cells (xcex4 cells) of the pancreatic Langerhans islet;
6. The agent for protection or amelioration of the function according to the above 1 or 2, wherein the pancreatic cell is B cells (xcex2 cells), A cells (xcex1 cells), D cells (xcex4 cells), and/or PP cells of the pancreatic Langerhans islet;
7. The agent for protecting pancreatic tissue function or the agent for ameliorating hypofunction of pancreatic tissue according to the above 3 or 4, wherein the pancreatic tissue is the pancreatic Langerhans islet;
8. The agent for protection or amelioration according to the above 1, 2, 5 or 6, which is an agent for protecting or ameliorating pancreatic endocrine function (insulin secretion ability, glucagon secretion ability and/or somatostatin secretion ability) or an agent for ameliorating pancreatic endocrine function disorder (insulin secretion ability, glucagon secretion ability and/or somatostatin secretion ability);
9. The agent for protection or amelioration according to the above 3, 4 or 7, which is an agent for protecting or ameliorating pancreatic endocrine function (insulin secretion ability, glucagon secretion ability and/or somatostatin secretion ability) or an agent for ameliorating pancreatic endocrine function disorder (insulin secretion ability, glucagon secretion ability and/or somatostatin secretion ability);
10. The agent for protection or amelioration according to the above 1, 2, 5, 6, or 8, wherein the cause for hypofunction or disorder of pancreatic cells is diabetes mellitus;
11. The agent for protection or amelioration according to the above 3, 4, 7 or 9, wherein the cause for hypofunction or disorder of pancreatic tissues is diabetes mellitus;
12. The agent for protection or amelioration according to the above 1, 2, 5, 6, or 8, wherein the cause for hypofunction or disorder of pancreatic cells is acute pancreatitis or chronic pancreatitis;
13. The agent for protection or amelioration according to the above 3, 4, 7 or 9, wherein the cause for hypofunction or disorder of pancreatic tissues is acute pancreatitis or chronic pancreatitis;
14. The agent for protection or amelioration according to the above 1, 2, 5, 6, or 8, wherein the cause for hypofunction or disorder of pancreatic cells is a sulfonylurea derivative;
15. The agent for protection or amelioration according to the above 3, 4, 7 or 9, wherein the cause for hypofunction or disorder of pancreatic tissues is a sulfonylurea derivative;
16. An agent for treating acute pancreatitis or chronic pancreatitis, which comprises as the active ingredient the agent for protection or amelioration as set forth in any one of the above 1, 2, 5, 6, and 8;
17. An agent for treating acute pancreatitis or chronic pancreatitis, which comprises as the active ingredient the agent for protection or amelioration as set forth in any one of the above 3, 4, 7 and 9;
16. An agent for protecting pancreatic endocrine tissues or an agent for ameliorating damaged pancreatic endocrine tissues, which comprises as the active ingredient a neurotrophic factor;
17. An agent for protecting pancreatic endocrine tissue function or an agent for ameliorating hypofunction of pancreatic endocrine tissues, which comprises as the active ingredient a neurotrophic factor;
18. An agent for protecting pancreatic exocrine tissues or an agent for ameliorating damaged pancreatic exocrine tissues, which comprises as the active ingredient a neurotrophic factor;
19. An agent for protecting pancreatic exocrine tissue function or an agent for ameliorating hypofunction of pancreatic exocrine tissues, which comprises as the active ingredient a neurotrophic factor;
20. The agent for protection or amelioration according to any one of the above 1 to 19, wherein the neurotrophic factor of the active ingredient is NGF (nerve growth factor), BDNF (brain-derived neurotrophic factor), CNTF (ciliary neurotrophic factor), NT-3 (neurotrophin 3), NT-4 (neurotrophin 4), NT-5 (neurotrophin 5), or NT-6 (neurotrophin 6);
21. The agent for protection or amelioration according to any one of the above 1 to 19, wherein the neurotrophic factor of the active ingredient is BDNF (brain-derived neurotrophic factor);
22. The agent for protection or amelioration according to any one of the above 1 to 19, wherein the neurotrophic factor of the active ingredient is CNTF (ciliary neurotrophic factor);
23. The agent for protection or amelioration according to any one of the above 1 to 19, wherein the neurotrophic factor of the active ingredient is NT-3 (neurotrophin 3);
24. The agent for protection or amelioration according to any one of the above 1 to 19, wherein the neurotrophic factor of the active ingredient is NT-4 (neurotrophin 4);
25. The agent for protection or amelioration according to any one of the above 1 to 19, wherein the neurotrophic factor of the active ingredient is NT-5 (neurotrophin 5);
26. The agent for protection or amelioration according to any one of the above 1 to 19, wherein the neurotrophic factor of the active ingredient is NT-6 (neurotrophin 6);
27. The agent for protection or amelioration according to any one of the above 1 to 19, wherein the neurotrophic factor of the active ingredient is NGF (nerve growth factor);
28. The agent for protection or amelioration according to any one of the above 1 to 19, wherein the neurotrophic factor of the active ingredient is GDNF (glia cell-derived neurotrophic factor);
29. The agent for protection or amelioration according to any one of the above 1 to 19, wherein the neurotrophic factor of the active ingredient is a trkA, a trkB and/or a trkC receptor agonist;
The meaning or definition of each term used in the present specification is explained below.
The xe2x80x9cagent for protectionxe2x80x9d means an agent for preventing disorder or hypofunction.
The xe2x80x9cagent for ameliorationxe2x80x9d means an agent for adjusting a damaged condition or a condition of hypofunction to the normal condition or normalizing it.
The xe2x80x9cneurotrophic factorxe2x80x9d means a physiologically active substance, which is secreted from the target cells for nerve growth, or by autocrine or paracrine, and promotes the growth, differentiation, or survival of neurons to form a neural circuit (synapse) in the living body. For example, the neurotrophic factor includes neurotrophins such as a nerve growth factor (hereinafter, abbreviated as NGF), a brain-derived neurotrophic factor (hereinafter, abbreviated as BDNF), a neurotrophin 3 (hereinafter, abbreviated as NT-3), a neurotrophin 4 (hereinafter, abbreviated as NT-4), a neurotrophin 5 (hereinafter, abbreviated as NT-5), and a neurotrophin 6 (hereinafter, abbreviated as NT-6); ciliary neurotrophic factor (hereinafter, abbreviated as CNTF); glia cell-derived neurotrophic factor (hereinafter, abbreviated as GDNF), etc. In addition, a modified recombinant neurotrophic factor produced by a substitution, a deletion, or an addition of a part of amino acid sequence of the naturally occurred neurotrophic factor sequence by a conventional technique may be included in the neurotrophic factor of the present specification, as far as it exhibits the similar physiological activity.
The xe2x80x9cpancreatic function disorderxe2x80x9d means pathologies, wherein the endocrine gland function or exocrine gland function of the pancreas is decreased or abnormally elevated. The endocrine gland function mainly means the secretion ability of insulin, glucagon and/or somatostatin, and the exocrine gland function mainly means the secretion ability of digestive enzymes (amylase, protease and/or lipase) into pancreatic juice. These secretion abilities can be evaluated by a conventional method being widely used in the clinical field, for example by measuring blood insulin level.
The xe2x80x9cprotection of pancreatic cellsxe2x80x9d means an action of protecting pancreatic endocrine gland cells and exocrine gland cells from degeneration induced by various causes, and it can be evaluated by examination of pancreatic tissue section under a microscope. Endocrine gland cells can specifically be stained by a conventional cell staining such as aldehyde fuchsin stain, and in the pancreatic Langerhans islet, B cells (xcex2 cells) can be stained by insulin immune staining, and A cells (xcex1 cells) can be stained by glucagon immune staining, and D cells (xcex4 cells) can be stained by somatostatin immune staining, and the stained patterns thereof can be observed. In addition, the structure of organellae can be examined by electron microscopy for evaluation.
The xe2x80x9cprotection of pancreatic tissuesxe2x80x9d means an action of protecting pancreatic endocrine gland tissues and exocrine gland tissues from degeneration induced by various causes, and it can be evaluated by examination of pancreatic tissue section under a microscope. The stained pattern of the tissues can be examined by a conventional cell straining such as hematoxylin-eosin stain, aldehyde fuchsin stain, etc. In addition, the structure of organellae can be examined by electron microscopy for evaluation.
The xe2x80x9ctrkA, trkB and/or trkC receptor agonistxe2x80x9d is a generic name for substances that are bound to trkA, trkB or trkC, which is among the trk gene expression products being known as receptors for xe2x80x9cneurotrophinxe2x80x9d, and activate them to exhibit their activities. Concretely, the known neurotrophin is, for example, NGF binding to trkA, BDNF and NT-4 binding to trkB, and NT-3 binding to trkC, etc. This concept includes not only modified neurotrophins (modified by amino acid substitution, deletion or addition or sugar chain modification), but also peptides and organic compounds of a lower molecular weight as far as they exhibit a binding ability and activating ability to trkA, trkB or trkC receptor, for example, phosphorilating activity of tyrosine residue.
The xe2x80x9csulfonylurea derivativexe2x80x9d is, for example, tolbutamide, acetohexamide, chlorpropamide, glyclopyramide, tolazamide, gliclazide, glibenclamide, glybuzole, glymidine, etc.